blame: add blame progress callback

include/git2/blame.h

@@ -76,6 +76,19 @@ typedef enum {
 	GIT_BLAME_IGNORE_WHITESPACE = (1<<6)
 } git_blame_flag_t;
 
+/**
+ * Blame progress callback.
+ *
+ * Called for each blame suspect.
+ *
+ * - 'suspect' is the id of the suspect commit.
+ *
+ * Returning a non-zero value will abort the blame.
+ */
+typedef int (*git_blame_progress_cb)(
+	const git_oid *suspect,
+	void *payload);
+
 /**
  * Blame options structure
  *
@@ -120,6 +133,9 @@ typedef struct git_blame_options {
 	 * The default is the last line of the file.
 	 */
 	size_t max_line;
+
+	git_blame_progress_cb progress_cb;
+	void *payload;
 } git_blame_options;
 
 #define GIT_BLAME_OPTIONS_VERSION 1

src/libgit2/blame_git.c

@@ -653,6 +653,16 @@ int git_blame__like_git(git_blame *blame, uint32_t opt)
 		if (!suspect)
 			break;
 
+		/* Callback to indicate that blame loading is still
+		 * in progress with the ability to abort the loading */
+		if (blame->options.progress_cb) {
+			const git_oid *id = git_commit_id(suspect->commit);
+			if ((error = blame->options.progress_cb(id, blame->options.payload))) {
+				/* Abort loading */
+				break;
+			}
+		}
+
 		/* We'll use this suspect later in the loop, so hold on to it for now. */
 		origin_incref(suspect);
 

tests/libgit2/blame/buffer.c

@@ -190,3 +190,36 @@ def\n";
 	check_blame_hunk_index(g_repo, g_bufferblame, 3, 11, 5, 0, "aa06ecca", "b.txt");
 	check_blame_hunk_index(g_repo, g_bufferblame, 4, 16, 2, 0, "00000000", "b.txt");
 }
+
+int blame_progress(const git_oid *suspect, void *payload)
+{
+	static int counter = 0;
+
+	counter ++;
+	cl_assert_equal_i(3.1416, *((double*)payload));
+
+	/* abort after the third suspect */
+	if (counter >= 3)
+		return -123;
+
+	return 0;
+}
+
+/*!
+ * \brief test_blame_buffer__abort_loading_blame
+ * Abort loading blame after a few suspects
+ */
+void test_blame_buffer__abort_loading_blame(void)
+{
+	git_blame_options opts;
+	git_blame_options_init(&opts, GIT_BLAME_OPTIONS_VERSION);
+
+	double number = 3.1416;
+
+	opts.progress_cb = &blame_progress;
+	opts.payload = &number;
+
+	cl_assert_equal_i(-123, git_blame_file(&g_fileblame, g_repo, "c.txt", &opts));
+	g_bufferblame = NULL;
+}
+